This post has been a long time in the making, because I wrote half a dozen essays on the nature of gameplay, science fiction, and open-ended missions and ended up here. However, those essays were all pretty academic and dull, so I didn't publish them... instead, I'm just going to talk about one set of mechanics that arose from that thinking, and why.
Because that won't be dull at all... sigh...
My big problem with most science fiction games is that there's no human element. Science fiction, in any medium other than video games, is used to explore the human condition. You can highlight some aspect of human life by creating some slightly magical setting that lets you focus on just that. In video games science fiction is used, exclusively, to shoot aliens. In every other medium, the aliens are standins for other humans that you don't know very well, so this makes video game sci fi pretty annoying to me.
In the past I've created some nonviolent sci fi prototypes, but I never really considered how to make the human side of things feel more human. How can you create gameplay around being human? I mean, you can script in some stuff, but I'm talking about core gameplay.
There are a few options. For example, you could make an entire game around parenting an android you built - sort of a Princess Maker: Android edition, or something.
But what if we wanted to have really open gameplay? I mean reaaaaaally open. Kerbal-level unguided play.
Okay, let's make it about starships. We'll set it in a zeerusty 60s space serial sort of environment. Science fantasy.
The core mechanic is not about creating the ship, but about creating the crew.
Let's start with the foundation: the chain of command. Or, rather, the tree of command, because below the leader it splits into three branches: security, science, and culture.
As your crew parades around the universe, they are exposed to stresses. For example, they might be chased by an angry dinosaur, a situation worth 80 "danger" stress.
It starts at the captain, who bites out a big piece, say 50%. This reflects her quick judgment: "RUN!" The remaining 40 danger is passed down to the security branch, since it's a security situation. The head of security takes another bite, say another 50%. This reflects him blasting at the dinosaur to try and scare it off. The remaining 20 danger is passed down to the final person on that branch, who similarly reduces it to, say, 10.
The 10 remaining danger is standing stress, and therefore reduces everyone's inspiration (basically health) by 10 points. Everyone starts with a lot, but you never regenerate any, so every point is valuable. More than that, however, one of the scientists is "clutzy", which means he is injured by danger-type stress, and receives a 10-point injury as well. IE, he got bitten or trampled or fell in a hole.
This will slowly recover, but while injured the scientist cannot participate in the chain of command.
Let's say the next stress is a scientific one - trying to figure out whether these dinosaurs are proper earth dinosaurs or what. The stress of not knowing is 80 points of science stress.
The captain's actual class is "scientist", so she takes a big bite out of that - say, 75%. Normally, she would then pass it down the chain of command... but the other scientist was injured, and can't participate. So the 20 science stress slips through and stands. This reduces everyone's inspiration 20 points, but the lead security guy is "dense" and takes "injury" from science stress. So he gets confused and panicky because of this weird, unknown situation, and will be useless until that "injury" heals and he calms down. This is a very bad injury, and will take quite a while to get over. So wandering back out into the badlands might be a bad idea.
You can see the bare foundations of the gameplay in this, but let's explore some more.
The key to making this kind of challenge interesting lies in making it predictable. The player has to know more or less what she's in for so she can create her crew for that purpose. This is not a game where you have a starship full of hundreds of crew that goes on interminable missions - it's more like Kerbal, where a mission is a huge event with a custom ship and a custom crew. Similarly, it is possible to chain and combine missions in interesting ways - the game doesn't ask you to, but it lets you. Hopefully this provides a graceful and endless learning curve as you choose to tackle ever more difficult and complex combinations of missions.
This means that if you land on Venus' plains, you'll always be chased by an angry dinosaur. But there are a lot of variables: you'll keep getting attacked by dinosaurs if you keep wandering around the plains. So you might venture into hills or forests, where different challenges await. Similarly, you might do research while in orbit to become adept at fighting dinosaurs, or keep someone in the orbital craft to watch for dinosaur herds and mark them on your map so you can avoid them...
But there need to be clear "success" states, not just an endless array of challenges. When you go to Venus, there has to be a reason. In Kerbal, the reason is always just to land on the surface. In our game, the conditions are a little more complex, so I think we can determine "success" by having specific modules on our starships or landers and fulfilling their requirements. For example, a zoology bay where you can examine dinosaurs in detail. A zoo bay for shipping them back to earth. A bacterial analysis chamber, a cultural exchange center, a gravitonic research chamber...
In this way we don't force the player to have a specific mission - in fact, they could just fly out there and dick around to learn the patterns of the world. But they can also choose which mission to undertake by attaching the proper module to their starship. And they can attach multiple modules. Or fly multiple starships out. Or use the same module on several different worlds. It's all very open.
The actions required to fulfill a mission module are predictable but not necessarily easy. For example, the zoology lab might require you to collect 3 samples from each Venusian terrain type - IE, survive 3 stress events from each terrain type. Others might require you to win by a certain amount, or leave crew behind, or get infected and then get healed, or any number of other conditions. These apply evenly to all applicable worlds - if you fly to Mars, you have the same kinds of requirements. Of course, not all worlds support all missions. Venus might not have any intelligent life, and a science base in the asteroid belt won't have different terrain types.
To reiterate, one of the biggest advantages of this approach is allowing the player to choose which mission modules to bring and letting them decide how to try to achieve them. This is powerful and easily modded, and a very good way to push the player to take on difficult challenges.
As you can tell, this isn't some kind of heavy-hitting plot generator. The stresses are pretty much limited to "in this kind of terrain, you get this kind of stress", with occasional bouts of "if you have X on you or Y with you, you get that kind of stress". The core challenge is to survive the stress you are exposed to. Since you never regain stress, it's basically the "fuel" of our game, and how quick you burn through it will determine how much you get done. Since everyone on the team suffers the same inspiration damage when stressed, it also really rewards you for breaking the team into smaller teams.
But the gameplay isn't simply building a hierarchy and then sending them out to the planets you want. There's a lot of other factors involved to make it more interesting.
One of these is technology, of course. Ships are built out of modules. The exact topology doesn't matter, so starships are just spines with each module as a donut, and shuttles are just tablet-shaped jets with a certain number of cylindrical internal slots. It's pretty simple, because our complexity is in the crew creation. Although simple, it is important and full of tradeoffs.
The heavier your ship, the slower it goes and the more fuel it burns - fuel regenerates, but you have to stand still to do that, so it comes down to more time wasted. And being stuck in space slowly eats away your inspiration, so it's best to minimize wasted time.
Many of the ship modules are about crew management, from simple crew quarters to security stations and even chapels. Some of these reduce the inspiration penalty for time passing. Others change the crew's stats (for example, giving them +10% against danger-type stresses). Others allow them to change relationships. Some of them help to repair injuries. Obviously, some of these are really nice to have on shuttles, but space is even tighter there.
Many of the modules are about interacting with the world. Sensors, cultural exchange centers, dissection labs, hospitals. And, of course, shuttle bays.
Many of the modules provide resources that allow other modules to function better. Computer stations, comm centers, gardens - these provide resources that other modules can burn to work faster and more efficiently.
Even though the ships are quite simple and abstract, they can get quite complex if you want them to. It might even be worth sending out unmanned ships/shuttles and connecting with them later...
But the ships are not the focus.
The crew is a bit more complex than a simple chain of command.
First off, each crew member has two aspects - a job and a weakness. Any crew member can try to deal with any kind of stress, but each job is best at a given kind. For example, a scientist will absorb 75% of science stress, 30% of culture stress, and 10% of danger stress. Or maybe you would prefer an academic? They absorb 50% science, 50% culture, and 10% danger. You can choose how focused or general you are. Certain kinds of very advanced modules can only be operated by a specific class, but that's unusual. It has no effect on their place in the chain of command - you can put anyone anywhere.
The weakness, of course, determines what injures them. Now, if someone's inspiration hits 0 they're disabled anyway, so nobody is completely immune to stresses of any kind... but everyone is also very vulnerable to particular stresses. There's actually more than 3 stresses - probably 9, although I haven't really settled on anything - so it's possible to have quite a large crew without repeating a weakness if you like.
Of course, each crew member also has an appearance and gender, which are only aesthetic.
Aside from their personal statistics, you also have interpersonal relationships. The chain of command is the biggest one. It can be reconfigured whenever you return to your ship, so it's pretty malleable. However, you can also define one personal relationship per crew member. For example, you can define person A as being the son of person B, person B as having married person C, person C being ancient rivals with D, and D being the mentor of A.
While each person can only spawn one relationship, relationships are two people, so people can and will be part of more than one relationship.
Each kind of relationship has a specific effect on the way stress and inspiration propagates. For example, a married couple will always "equalize" their inspiration. While no added inspiration will be gained, you could have one person exposed to a lot more stress and it would equalize to half on each. Because of this, married couples are usually split up into different teams so they suffer different amounts of inspiration damage. A parent and child relationship works such that the injuries they suffer regenerate faster when they are on the same team, and so on.
These relationships cannot be changed easily. However, it is possible: several modules produce social points, which can then be spent to establish new connections or break old ones - although which kinds of relationship depend on the module in question. This is invaluable on very long missions, because you'll lose a lot of inspiration on the flight and you'll need as many perfectly configured social links as possible to survive.
Anyway, that's the idea.
The core point is that we let the player create her own arbitrarily complex missions, but with crew instead of rocket parts.